[annie123 (OP)]

After listening to a NS podcast about RNA I related something Joan Steitz said   about her research, that 'many viruses make non coding RNAs to manipulate cells they live in to help with their own life cycles.' This suggests to me that what the virus makes is separate from the essential composition of the virus itself, and the virus itself manufactures a new RNA strand. In a group where we were discussing this, another person insisted that this is  not the case. She said:
Quote:  My understanding (although I do not know much about viruses) is that the virus has no machinery of its own to do the manufacturing of itself (RNA) but engineers the host cell to produce more particles of itself - the RNA virus.  So it could also direct the host cell to manufacture the non-coding RNA that you refer to I suppose.  Does that make sense?  Anyhow, it really does not matter too much which interpretation is correct as it does not alter the final result!

Can the virus create other stuff itself or just get the host cell to do the job as person B says? And does this make a difference to the final result?

Thanks.

[schneebfloob]

Viruses can't really do anything by themselves, however they can carry functional enzymes e.g. reverse transcriptase in the case of HIV and other retroviruses. These enzymes are not manufactured 'in-house' by the viruses, but get produced by the host cell that is infected and are then packaged into the new viral particles that then escape the cell. This means that when the virus goes on to infect a cell there may be active proteins released to do some dirty work. The same thing applies to ncRNAs. These will be transcribed from the viral genomic material by the host cell machinery upon infection, and may affect other cellular processes to help out the virus.

I don't think the statements contradict each other, but it's just how the first quotation is phrased.

Hope that helps

[evan_au]

Adding to schneebfloob:
The virus is made up of proteins & sugars, plus RNA/DNA (the instructions to make more viruses).

However, if the cell detects that it is infected, it may take evasive actions, eg commit suicide (apoptosis) to prevent making more viruses. Hence the virus dies out.

Viruses have mechanisms for getting inside the cell (eg host-specific proteins on the coat), and once inside, hijack the cell machinery. Some of these hijacking actions may be to turn off apoptosis, halt production of some host proteins or increase production of other host proteins. Some of these functions can be achieved by RNA binding to regulatory regions of the host cell's DNA.

While these non-protein-coding sections of viral RNA do not produce a part of the virus structure that leaves the cell, they are still essential for the viral life-cycle, and are included in the viral RNA that leaves the cell.

(...or should that be "viral death-cycle", since by the standard definitions, viruses aren't alive?)

[annie123 (OP)]

Thanks to both. Re phrasing of the question - I took it from Joan Steitz- the Albany medal winner for RNA research - and so thought it was accurate in terms of saying the virus  DID something itself, i.e. acted as a creative agent. The other person in the conversation more or less said this was nonsense as viruses couldn't make things themselves, but got cells to do it for them. Well, getting a cell to do something surely implies a controlling agency and so an active participant. And then there's the question of living too - in that the definition of what is alive- what is life - is so elusive. I don't think the present criteria are accurate any more in terms of something being able to act independently, even if it can't reproduce(where do mules come n this spectrum? This is another question of course which I think has been on the forum with no real resolution.)
Also, my 'friend's' claim that the end result was the same anyway isn't really satisfactory in that it seems to me the process of something happening does make a difference in terms of the nature of the agencies involved.

[yellowcat]

Some viruses can cause a reorganisation of cellular membranes to form  complex subcellular microenvironments called virus factories.
These locations concentrate viral  proteins, virus genomes and host proteins  required for viral replication and also protect against the cells antiviral defences.
http://www.virology.ws/2010/07/22/the-virus-and-the-virion/